1. Field of the Invention
The present invention relates to a portable gas alarm device.
2. Description of the Background Art
There are generally frequent occasions when it may be possible in, for example, underground job sites or gateways, or other places where persons enter, or working regions that air in an environmental atmosphere is in a dangerous state, or will become a dangerous state, such as occasions when a harmful gas or gases such as carbon monoxide gas and hydrogen sulfide gas may possibly be contained in air in such an environment, or when the oxygen gas concentration in air may possibly be lowered.
When the air in the environmental atmosphere has become a dangerous state to persons due to high concentration of the harmful gases contained or low oxygen gas concentration, it is necessary to detect the situation.
From such a demand, there have heretofore been proposed various types of portable gas alarm devices. Since the conventional portable gas alarm devices are generally large in size, however, they are fabricated as, for example, shouldering type and involve problems that they are considerably unhandy to carry and are being a great obstacle to practice the intended work or the like.
The present invention has been completed on the basis of the foregoing circumstances and has as its object the provision of a portable gas alarm device which is easy to be fabricated as a small-sized one handy to carry and high in convenience for use.
According to the present invention, there is thus provided a portable gas alarm device comprising a gas alarm device body having a casing flat in whole and a fitting member provided on the casing to fit it to a human body of a person, wherein the gas alarm device body has a control circuit board provided so as to extend to the direction of the flat plane of the casing inside the casing, a display mechanism is arranged in a central area on the front surface side of the control circuit board, a gas sensor and an alarm buzzer are arranged on the right and left sides of the display mechanism, and a battery fitting chamber is provided on the back surface side of the circuit board.
In the above-described construction, a gas sensor holding part for holding the gas sensor and an alarm buzzer holding part for holding the alarm buzzer may preferably be formed on surface portions of the casing of the gas alarm device body in a state projected upper than the surface of the central area in which the display mechanism is arranged.
A light emitting part for alarm and at least one operating button may preferably be provided on the upper and lower sides of the display mechanism on the front surface side of the control circuit board in the gas alarm device body. A vibration generator for alarm may preferably be provided in the gas alarm device body.
The concentration of a gas detected, time and a life of a battery fitted in the battery fitting chamber may be displayed in the display mechanism of the gas alarm device body.
The gas sensor may be held detachably in the gas sensor holding part in the casing of the gas alarm device body so as to be interchangeably.
The fitting member may preferably be one suitable for use in fitting the gas alarm device body to a person""s wrist or in fitting the gas alarm device body to a person""s wear.
In the above construction, one selected from among an oxygen gas sensor, hydrogen sulfide gas sensor and a carbon monoxide gas sensor may preferably be used as the gas sensor.
According to the above-described construction, the gas sensor and alarm buzzer are arranged respectively in areas on both right and left sides of the central area, in which the display mechanism is arranged, on the front surface side of the control circuit board arranged in the casing, and the battery fitting chamber is provided on the back surface side of the control circuit board, whereby the parts relatively great in area or volume among the essential component parts for the gas alarm device are rationally arranged, so that the gas alarm device body can be constructed into a small-sized and thin-walled one as a whole, and moreover the fitting member is provided in the gas alarm device body, so that a portable gas alarm device having actually high convenience is provided.